Unipolar generator is known in which electric motor is used as a power source powering the high voltage source. This motor is coupled to a propeller for placing in air flow of the ventilation and air conditioning systems (refer to JP2004 03 1297A).
The main drawback of this invention consists in that it does not perform an operation and does not include elements designated for cleaning of air ionizing electrodes from dust.
Indeed, such ion generator mounted at the air-duct outlet on the premises ceiling presents difficulties for periodic cleaning of electrodes from dust, particularly in high ceiling premises.
Also a bipolar generator is known which contains a ventilator and a cleaning device that includes arms, each of the arms for cleaning a corresponding ionizing electrode of the ionizing electrodes from dust (refer to U.S. Pat. No. 5,768,087).
In this invention the ionizing electrodes are mounted on the stationary part of the ventilator, whereas the device for cleaning the electrodes from dust is mounted on the propeller.
The electrodes are shaped as needles, each of the electrodes is made from non-elastic wire, whereas the cleaning device constitutes a brush.
The centrifugal force in the device described in U.S. Pat. No. 5,768,087 Fc=m·ω2R (where ω is the angular velocity, R is the radius) the mass (m) is located at the end of cleaning device opposing the end contacting with the ionizing electrodes.
The cleaning device itself is limited by the dimensions of the propeller zone situated outside the airflow.
Hence, the radius is small and consequently the angular velocity is low.
At the same time when an electric motor of a certain size is used as a wind generator the rotation velocity of its propeller is always 2-3 times as low as that for the same motor used as an electric engine.
A three-fold decrease in the velocity for the same radius would require a nine times increase in the mass in order to yield the same centrifugal force.
This condition is unacceptable for the use of an electric motor as a power source because it renders an increase of the propeller weight and the value of the propeller starting rotation moment.
Also bipolar ion generation methods and ion generators are known wherein the air ionizing electrodes and mounted on the ventilator propeller (refer to WO 2004 008597A1 or JP 2004 362 855A). In the devices described in these publications no cleaning of the ionizing electrodes from dust is referred to.
One of the common drawbacks of all the known inventions consists in that the air ionizing electrodes are shaped either as sharp tip needles or as planar triangle structures (refer for example to Patent JP 2004 362855A).
During ionization metal emission occurs from the needle tips and in due course they become blunter which results in the decreased ion emission.
Another common drawback of all the mentioned inventions consists in the constant level of ions at the ion generator outputs.
This results in that the air flow velocity change, for example towards the velocity increase, causes the decrease of ion concentration in the premises.
On the one hand the decrease of ion concentration reduces the efficiency of the bacteria and viruses inactivation, whereas on the other hand the limit of the ion concentration level indoors is determined by a standard.
Hence the ion concentration in the premises should preferably be maintained constant and lower than the value set in the applicable standard at any changes of the air flow velocity.